A main feature of Scott Farm is an Effluent Irrigation System (EIS) for treating dairy wastewater from both Lye and Scott Farms, with research trials conducted on both farms able to utilise the nutrients from this system.

Until 2012, Scott Farm used an 'environmentally friendly' Advanced Pond System (APS) for effluent storage and treatment. Like many older effluent systems, the APS became difficult to operate within compliance limits over time and spurred DairyNZ to install a new system, the EIS, while still retaining some of the APS infrastructure to minimise the cost of the upgrade. The EIS was designed and developed to cope with around 12,000 m3 of effluent, 72,000 m3 of wash water and 7,000 m3 of rainwater annually. Given the cost of upgrading, meeting effluent compliance requirements for years to come was also a key priority.

So how does the EIS work? Effluent from both Lye and Scott Farm is piped to the EIS located on Scott Farm. It is collected in a large sump and then pumped over a 1.2 m static “wedge wire” screen separator, which separates fibres down to 1mm. The screened liquid flows through a 150 mm gravity discharge pipe and is then pumped to a storage pond. T solids slide into a concrete bunker and are periodically moved to a composting area. The solids are used to fertilise and condition cropping areas on both farms. The bunker is large enough to store solids for a longer period, giving plenty of flexibility for emptying. With the solids sorted, that just leaves the liquid.

From the storage pond, the liquid is pumped over a total area of 112 ha, with about 50% of the land being on each farm. The area is split into seven irrigation zones, requiring 168 K-line pods. Application depths can be adjusted from 5-25 mm either manually or by phone text, so the Farm Manager can keep control of effluent application remotely.

Soil moisture content is regularly monitored to ensure saturated soils are not irrigated, mitigating the risk of run-off. However, storage of liquid manure for long periods can then become a risk in itself. To counteract this, there are actually two ponds that store liquid. The first pond has a working capacity of 4,552 m3 while an overflow pond can take an additional 1,686 m3, in total equating to around 28 days storage. And this is where the old infrastructure was put to use; converting the old APS ponds into the new EIS ponds to keep costs down.

The EIS has other financial advantages; being able to apply the liquid manure whenever soil conditions are optimal means that the overall fertiliser bill can be cut by around $27,000 per annum. More muck than buck!